Sliding link safety latch

ABSTRACT

Safety latch has a base securable to a door and a catchplate securable to the adjacent doorframe, or vice versa. An intermediate link is slidably and pivotally mounted in the base, and a latch link is pivotally mounted to the intermediate link and selectively engageable in the catchplate. When the latch link and intermediate link are folded into the base and are slid to the non-engagement position, they are locked in place. When they are slid to a position where the latch link is engaged with the latchplate, the links can unfold out to permit the door to open a limited amount.

United States Patent 1191 Markovitch 45] D 9, 1975 SLIDING LINK SAFETYLATCH 2,462,282 2/1949 Pickford 292/247 x [75] Inventor: BrankoMarkovitch, Hawthorne, 3,563,592 2/1971 Preston 292/263 Cahf' PrimaryExaminerRichard E. Moore [73] Asslgnee: Samuel P. Simmons, Lomita,Calif. Attorney, Agent, or FirmJoh1n Holtrichter, Jr.

22 Filed: 24 7 1 19 4 57 ABSTRACT [21] Appl' 436097 Safety latch has abase securable to a door and a catchplate securable to the adjacentdoorframe, or 52 US. Cl 292/263; 70/93 viee verea- An intermediate linkis Slidably and p 51 Int. cl. E05C 17/48 y mounted in the base, and alateh link is pivetally [58] Field of S h 292/113 263 247 mounted to theintermediate link and selectively en- 7O/93 gageable in the catchplate.When the latch link and intermediate link are folded into the base andare slid [56] Ref Ci d to the non-engagement position, they are lockedin UNITED STATES PATENTS place. When they are slid to a position wherethe latch 526,164 9/1894 Phelps 292/263 hnk ls engaged wlth thelatchplate the hnks can un- 906,305 12/1908 Schacht 2,407,900 9/1946Paul 70/93 fold out to permit the door to open a limited amount.

12 Claims, 10 Drawing Figures SLIDING LINK SAFETY LATCH BACKGROUND OFTHE INVENTION This invention is directed to a safety latch for fasteningto a door to permit the door to be opened a limited distance.

When the security of person or property is involved, door locks andlatches are required. Many types of locks have been created to retaindoors in closed position, except at the manipulation of the owner. Withrespect to safety latches, there are situations where the person insidedesires to have his door open only a limited amount. In these cases,ventilation or viewing through the limited door opening are possible.For many years, chains have been employed in this service. Chains aredisadvantageous because they are difficult to manipulate noisy inoperation, and noisy when they are hooked up on the door and the door isin normal use. Furthermore, the chain structures are usually low instrength due to the end fittings thereon and the fact that such chainstructures are generally attached to relatively weak door moldings.Thus, there is need for an improved safety latch structure.

SUMMARY OF THE INVENTION In order to aid in the understanding of thisinvention, it can be stated in essentially summary form that it isdirected to a safety latch for mounting upon a door member and upon adoor frame member. The safety latch has a base securable to one of thedoor members, as well as a latchplate securable to the other doormember. An intermediate link slidably mounted in the base pivotallycarries a latch link which is engageable with a latchplate so that, whenit is engaged, the structures are coupled together and swing out tolimit the opening of the door.

It is thus an object of this invention to provide a safety latch ofconveniently operable and economic construction which provides fullsecurity.

It is another object to provide a safety latch structure which has aslidable intermediate link which locks the intermediate link and latchlink in the base during nonuse of the safety latch and which permitssliding of the intermediate link out of lock position to a positionwhere the latch link engages the latchplate.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The presentinvention, both as to its organization and manner of operation, togetherwith further objects and advantages thereof, may best be understood bymaking reference to the following description, taken in conjunction withthe accompanying drawings, in which like reference characters refer tolike elements in the several views.

BRIEF DESCRIPTION OF THE DRAWING FIG. 5 is a perspective view of anotherembodiment of the safety latch and door lock of this invention;

FIG. 6 is a section therethrough similar in aspect to the section ofFIG. 3;

FIG. 7 is a side-elevational view of another embodiment of the safetylatch of this invention;

FIG. 8 is a section therethrough of similar aspect to the section ofFIG. 6;

FIG. 9 is a bottom-plan view of the safety latch of FIG. 7, with theintermediate link and latch link extended; and I FIG. 10 is aperspective view of a portion of a latchplate adapted for use with thelatch links shown in the embodiments of FIGS. 59.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 through 4 show apresently preferred embodiment of safety latch 10 of this invention.Safety latch 10 has three major parts. Base 12 is arranged forsecurement by any conventional means such as screws 12 on door 14adjacent the edge thereof away from the door hinges. Latchplate 16 issecured by means of screws, for example, against the doorframe 18adjacent the location of base 12. I

Intermediate link 20 carries sliding pivot pin 22 through its inner end.Sliding pivot pin 22 also engages through slots 24 and 26 in theupturned sides of base 12; thus when intermediate link 20 liessubstantially parallel to the bottom of base 12, its pin 22 can slidealong the length of slots 24 and 26. Spring 28 is secured to the base 12by a rivet 29 and engages against pin 22 to resiliently detent the pinin either of its end positions along the slots 24 and 26. In FIGS. 1 and2, the intermediate link is positioned in its retracted rightmostposition. In FIGS. 3 and 4, pivot pin 22 is detented into the left endof the slots.

Hinge pin 30 pivotally interengages' between the outer end ofintermediate link 20 and the inner end of latch link 32, and handle 34is secured to the outside surface of latch link 32 for convenience inmanual engagement. In this embodiment, the outer end of latch link 32has a positive tee 36 which engages into a tee slot 38 in a hollowcylindrical end portion 39 of the latchplate 16 However, in manyapplications it may be desirable that the link carry a tee slot andthelatchplate carry the tee, as illustrated in FIGS. 5-10, for example.

The parts are dimensioned, as seen in FIGS. l and 2, so that latch link32 folds to overlie intermediate link 20 and lie between the sides ofbase 12. When. folded into such position andslid to the right, as shownin tently come loose. When they are moved to the left, as

seen in FIG. 3, latchplate 16 is positioned so that tee 36 enters teeslot 38 to lock therein, see FIG. 3. From this position, the linksunfold as the door is swung open to the extent permitted by the links.The width of the tee slot retains tee 30 as long as the latch link isswung out. Thus, the secure outer limit for door-hinging is achieved.

Safety latch 44 is generally illustrated in FIGS. 5 and 6. It is anotherspecies of the safety latch and illustrates a structure having base 46,intermediate link 48, and

3 latch link 50 similarly interrelated to the corresponding parts insafety latch 10. The same sliding pivot pin 22 and hinge pin 30 areinvolved. The outer ends of latch link 50 have a tee slot 51 therein forengagement on a corresponding tee 52 in the associated latchplate 53, asshown in FIG. 10.

The principal difference between safety latch 10 an safety latch 44 isin the locking structure which retains the links in place in the basewhen they are not needed for latching duty. Sliding lock 54 slidablyheld in base slots 55 has a locking cover 56 which engages over latchlink 50 when the entire structure is in the inoperative, lockedposition.

When engagement of latch link 50 with its corresponding latchplate 53 isdesired in order to prevent the door from being opened, sliding lock 54is slid to the left by manual engagement with its locking handle 58 tothe position shown in FIGS. and 6. This sliding motion moves theintermediate link 48 and latch link 50 halfway to the left to engage inthe slots 51 defining the tee 52 in the latchplate 53. This serves as apositive lock for the door because the links cannot swing out; they areheld down by locking cover 56. When safety latching is desired, thelinks are pressed to the left by means of link handle 50a to be detentedin the left position by a detent spring 57. This motion moves latch link50 into its latch-engagement position. When sliding lock 54 is moved tothe right, the hinge pin junction between the links is released and thelinks can swing out to a door-limiting position. Thus in the safetylatch 44, sliding lock 54 retains the link structure in folded positionduring nonuse and selectively retains the links in folded position afterengagement of the latch link 50 to serve as a closed door-retaininglatch. As can be seen in FIG. 6, the spring 57 is retained in positionby a rivet 59 and has two lobes 57a and 57b to detent the oppositepositions of the links. Although not necessarily essential to the basicoperation of the present invention, in all embodiments of the inventionthe latch link is preferably biased by the detent spring toward thelatchplate when the latch link is moved into its latchplate engagementposition, and the distance between the plate and the base is such thatthe outer extremity of the latch link contacts the latchplate and exertsa pressure against it caused by the bias provided by the spring.

FIGS. 7 through 9 illustrate safety latch 60, which is anotherembodiment of the safety latch of this invention. Safety latch 60 hasthe same basic parts as the previously described embodiments, namely abase 62 with screw-accepting lobes 63, intermediate link-64, and a latchlink 66. Intermediate link 64 is secured to the base by means of slidingpivot pin 68 engaged in slots 69 of the base. Hinge pin 70 hinges latchlink 66 to the outer end of the intermediate link 64. When the structureis slid to the latching position, to the left, the latch link 66 extendsinto engagement with its corresponding latchplate 53 (see FIG. underbias pressure provided by detent spring 71. When latched in that manner,the links can unfold to limit the amount of door opening, as previouslydescribed with respect to safety latch 10. When folded, the links areslid to the right, to the position shown in FIG. 7, where locking isaccomplished. Locking of the links in the folded position is managed bymeans of lock pin 72 which has head 74 thereon over a reduced diameterneck 75. The head passes through, and the neck engages, in keyhole slot76 to hold the links in position. Thus, sliding the links with respectto the base locks andunlocks them by 4 means of the keyhole slotstructure. An elongated slot 78 is provided in the intermediate link 64in order to allow free movement of this link without engagement with thelock pin 72.

From the foregoing it should be evident that there has been describedsafety latches which are conveniently operable and of economicconstruction and which provide full security while allowing a door to beopened a limited amount.

It should be understood that the materials used to fabricate the variousembodiments of the invention are not critical and any materialexhibiting desired qualities such as ease of fabrication, strength,etc., may be used. For example, solid or brass-plated steel or analuminum alloy and possibly even some synthetic materials may beutilized. Furthermore, any conventional manufacturing process such ascasting, machining, stamping, etc., may be used. I i I It should also beunderstood that although several embodiments of the invention have beendescribed, the invention is susceptible to numerous modifications andembodiments within the ability of those skilled in the art and withoutthe exercise of the inventive faculty. For example, the latchplate maybemounted on the door and the safety latch link mechanism may be mountedon the door frame. Accordingly, such modifications and embodiments aredeemed to be within the spirit, scope and contemplation of thisinvention.

I claim:

l. A safety latch for mounting upon a door member and upon an associateddoor frame member to selectively permit the door to swing freely open orto permit the door to swing open a positively limited amount, saidsafety latch comprising:

a stationary latchplate for mounting on one of the door members, saidlatchplate having an engagement opening therein;

a base for mounting upon the other door member;

an intermediate link slidably and pivotally mounted with respect to saidbase;

a latch link pivotally mounted with respect to said intermediate link,said latch link having a nose for engagement into said engagementopening of said latchplate only when the door is in closed position sothat said intermediate link and said latch link unfold and pivot withrespect to each other and with respect to said base to limit dooropening.

2. The safety latch of claim 1 wherein a sliding pivot pin interengagesbetween said intermediate link and said base to permit sliding andpivoting of said intermediate link with respect to said base.

3. The safety latch of claim I wherein a stop is secured to said baseand said latch link is retained by said stop with respect to said basewhen said links are folded and slid in a retracted position withrespectto said base.

4. The safety latch of claim 3 wherein said stop comprises a cross stopextending across the top of said base and engaging over said latch linkwhen in its folded retracted position.

5. The safety latch of claim 4 wherein said stop is fixed on said base.

6. The safety latch of claim 4 wherein said stop is slidably movable onsaid base so that said stop can be moved to a position wherein saidengagement nose on said latch link is extended into said engagementopening in said latchplate and said latch link is retained by said stopin folded position with respect to said base to hold the door in itsclosed position.

7. The safety latch of claim 6 wherein said engagement opening in saidlatchplate and said engagement nose on said latch link are in the formof a tee and a tee slot constructed so that said engagement nose canengage into said engagement opening when the door is closed, and saidengagement nose is prevented from disengagement from said engagementopening when the door is opened.

8. The safety latch of claim 7 wherein the sliding pivot pininterengages between said intermediate link and said base to permitsliding and pivoting of said intermediate link with respect to saidbase.

9. The safety latch of claim 3 wherein said stop comprises a postmounted on said base, said post having a head thereon, said headengaging through a keyhole slot in said latch link so that said latchlink is retained with respect to said base when said latch link is inits retracted position and said latch link is free to swing out of saidbase when said latch link is in its extended positron.

10. The safety latch of claim 1, also comprising spring means mounted onsaid base and slidably cooperating with said intermediate link forindexing and biasing the sliding movement of said intermediate link.

11. The safety latch of claim 1, wherein said engagement opening in saidlatchplate is in the form of a tee and said engagement nose on saidlatch link is in the form of a tee slot, said tee and tee slot beingconstructed so that said engagement nose can engage said engagementopening when the door is closed, and said engagement nose is preventedfrom disengagement from said engagement opening when the door is opened.

12. The safety latch of claim 1, wherein said engagement opening in saidlatchplate is in the fonn of a tee slot and said engagement nose on saidlatch link is in the form of a tee, said tee slot and tee beingconstructed so that said engagement nose can engage said engagementopening when the door is closed, and said engagement nose is preventedfrom disengagement from said engagement opening when the door is opened.

1. A safety latch for mounting upon a door member and upon an associateddoor frame member to selectively permit the door to swing freely open orto permit the door to swing open a positively limited amount, saidsafety latch comprising: a stationary latchplate for mounting on one ofthe door members, said latchplate having an engagement opening therein;a base for mounting upon the other door member; an intermediate linkslidably and pivotally mounted with respect to said base; a latch linkpivotally mounted with respect to said intermediate link, said latchlink having a nose for engagement into said engagement opening of saidlatchplate only when the door is in closed position so that saidintermediate link and said latch link unfold and pivot with respect toeach other and with respect to said base to limit door opening.
 2. Thesafety latch of claim 1 wherein a sliding pivot pin interengages betweensaid intermediate link and said base to permit sliding and pivoting ofsaid intermediate link with respect to said base.
 3. The safety latch ofclaim 1 wherein a stop is secured to said base and said latch link isretained by said stop with respect to said base when said links arefolded and slid in a retracted position with respect to said base. 4.The safety latch of claim 3 wherein said stop comprises a cross stopextending across the top of said base and engaging over said latch linkwhen in its folded retracted position.
 5. The safety latch of claim 4wherein said stop is fixed on said base.
 6. The safety latch of claim 4wherein said stop is slidably movable on said base so that said stop canbe moved to a position wherein said engagement nose on said latch linkis extended into said engagement opening in said latchplate and saidlatch link is retained by said stop in folded position with respect tosaid base to hold the door in its closed position.
 7. The safety latchof claim 6 wherein said engagement opening in said latchplate and saidengagement nose on said latch link are in the form of a tee and a teeslot constructed so that said engagement nose can engage into saidengagement opening when the door is closed, and said engagement nose isprevented from disengagement from said engagement opening when the dooris opened.
 8. The safety latch of claim 7 wherein the sliding pivot pininterengages between said intermediate link and said base to permitsliding and pivoting of said intermediate link with respect to saidbase.
 9. The safety latch of claim 3 wherein said stop comprises a postmounted on said base, said post having a head thereon, said headengaging through a keyhole slot in said latch link so that said latchlink is retained with respect to said base when said latch link is inits retracted position and said latch link is free to swing out of saidbase when said latch link is in its extended position.
 10. The safetylatch of claim 1, also comprising spring means mounted on said base andslidably cooperating with said intermediate link for indexing andbiasing the sliding movement of said intermediate link.
 11. The safetylatch of claim 1, wherein said engagement opening in said latchplate isin the form of a tee and said engagement nose on said latch link is intHe form of a tee slot, said tee and tee slot being constructed so thatsaid engagement nose can engage said engagement opening when the door isclosed, and said engagement nose is prevented from disengagement fromsaid engagement opening when the door is opened.
 12. The safety latch ofclaim 1, wherein said engagement opening in said latchplate is in theform of a tee slot and said engagement nose on said latch link is in theform of a tee, said tee slot and tee being constructed so that saidengagement nose can engage said engagement opening when the door isclosed, and said engagement nose is prevented from disengagement fromsaid engagement opening when the door is opened.